Printing plate clamping device for a printing press



Oct. 4, 1966 K. LANGER 3,276,365

PRINTING PLATE CLAMPING DEVICE FOR A PRINTING PRESS Filed Oct. 29, 1964 Inventor- KHRL AHA GER fir TOR/V575 United States Patent 3,276,365 PRINTING PLATE CLAMPING DEVICE FOR A PRINTING PRESS Karl Langer, Heusenstamm, near Offenbach (Main), Germany, assignor to Roland ()lfsetmaschinenfabrik Faber 8: Schleicher A.G., Offenbach (Main), Germany, a German firm Filed Oct. 29, 1964, Ser. No. 407,506 Claims priority, application Germany, Apr. 25, 1964, R 37,780 Claims. (Cl. 101-4151) The present invention relates to a device for tautly clamping a bendable plate upon the cylinder of a printing press and, more particularly, upon a plate cylinder having a lengthwise slot for clamping therein the respective ends of the plate.

There are known devices of this kind in which the plate ends are clamped and stretched by means of wedge-shaped bars lengthwise displaceable in the slot, or by means of bars which are tangentially or radially displaceable in the slot. Devices of this kind are comparatively complex and expensive.

It is a broad object of the invention to provide a novel and improved device of the general kind above referred to which is rugged and simple in construction and by means of which the plate can be .tautly clamped in a simple and reliable manner in a minimum of time and which also permits a rapid and convenient detachment of the plate from the cylinder.

A more specific object of the invention is to provide a novel and improved clamping device of the general kind above referred to which holds both plate ends tightly against wall portions of the cylinder defining the slot therein, thereby strongly securing the plate to the cylinder.

The aforementioned objects, features and advantages and other objects, features and advantages which will be pointed out hereinafter, are attained by providing in the cylinder slot a rotatable shaft or spindle having in its peripheral wall a plurality of longitudinal teeth, the length of which is at least equal to the width of the plate to be clamped and tensioned. These teeth engage equally long teeth on one side of a clamping bar interposed between said shaft and one of the side walls of said slot closely adjacent thereto.

To clamp and tension the plate, one end of the plate is inserted into the narrow gap between said side wall of the slot and the adjacent side of the clamping bar which is left flat or smooth and the other plate end is fitted between the engaged teeth. When now, the shaft is turned in one direction the respective end of the plate is pulled into the slot while the other is held in the slot, whereby the plate is tautly clamped about the cylinder. Release of the plate is efi'ected by simply turning the shaft into the opposite direction.

To increase further the strength with which the plate ends are clamped in the slot, the bent-off end portion of the plate inserted in said gap may have on its side facing the respective slot wall a pressed-in lengthwise rib engaged with a corresponding lengthwise groove in said slot wall, thereby forcing the respective plate end into intimate con tact with said slot wall.

The invention also encompasses a support of the shaft along its entire length by providing ribs or bars in the slot extending along the length of the shaft, parallel to the rotational axis thereof. In addition, to prevent bend- 3,276,365 Patented Oct. 4, 1966 ing of the shaft under stress, the bars also prevent access of dust or abrasive particles to the bearings of the shaft.

In the accompanying drawing a preferred embodiment of the invention is shown by way of illustration and not by way of limitation.

In the drawing:

FIG. 1 is a cross-sectional view of a plate cylinder provided with a clamping device according to the invention, an initial step of the clamping operation being shown.

FIG. 2 is a sectional view similar to FIG. 1, but a further advanced step of the clamping operation being shown.

FIG. 3 is a sectional view similar to FIG. 2 and showing the completed clamping operation, and

FIG. 4 is a fragmentary longitudinal sectional view of the clamping device.

Referring now to the figures in detail, there is shown a plate cylinder 1 including a lengthwise peripheral slot 2 having a constricted mouth 20. The slot may be of generally circular cross-section and extend along the entire width of cylinder 1; it should have a length at least equal to the width of plate 10 to be clamped. The shaft is rotatably supported in slot 2. The support of the shaft is diagrammatically indicated by trunnions 3a extending into walls 14 which may be visualized as constituting part of the frame structure of the press. Rotation of the shaft is effected by means of .a conventional, preferably selfarresting worm gear 15. Worm gears of this kind are well known in the art.

The shaft is formed with lengthwise teeth 4 in mesh with teeth 5 formed of one side of a bar 6. The other side of the bar is left substantially flat or smooth. The fiat side of bar '6 faces a straight wall portion 7 of slot 2. A shallow recess may be provided in the flat. side of bar 6 to improve the grip of the bar on the plate 10. The wall portion 7 includes a lengthwise groove 8 which may have a V-shaped cross-section. Groove or notch 8 is engageable with a correspondingly shaped rib .1;1 pressed into the bent-off end portion 9 of plate 10 and extending across the width of the plate.

To clamp a blanket to the cylinder the bent-off portion 9 of the plate is first inserted between slot wall 7 and bar 6, as it is shown in FIG. 1. The respective opposite end portion 12 of the place is fed between the teeth on shaft 3 and on bar 6 as it is indicated in FIG. 2. Plate end 12 is preferably preformed with teeth as it is also shown in FIG 2.

When now shaft 3 is rotated in clockwise direction, the plate end 9 is retained between bar 6 and slot wall 7 but remains stationary in the slot and the other plate end 12 is pulled deeper between the teeth on the shaft and the bar, as it is shown in FIG. 3.

As it is evident, the tensioning of plate 10 can be readily controlled by the angle through which shaft 3 is turned. Release of the plate is effected by turning shaft 3 in counterclockwise direction.

To prevent deformation of shaft 3 and to protect the bearings of shaft 3 against access of dust and abrasive particles to the shaft bearings, two bars 13 are provided which are fitted in appropriate grooves 13a in the cylinder. The bars extend lengthwise of slot 2 and parallel to the rotational axis of shaft 3. Instead of separate bars 13, fixed ribs may of course also be provided. The two bars 13 are disposed substantially opposite the area of engagement between shaft 3 and bar 6. The bars are preferably made of low wear material which also has suitable friction characteristics. Bars made of bronze or hardened steel have been found suitable.

While the invention has been described in detail with respect to a certain now preferred example and embodiment of the invention, it will be understood by those skilled in the art, after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended therefore to cover all such changes and modifications in the appended claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A device for tautly clam-ping a bendable printing plate about the cylinder of a printing press, said device comprising a cylinder having a lengthwise peripheral slot, a shaft rotatably supported in said slot, said shaft having several lengthwise peripheral teeth, a clamping bar fitted between said shaft and one side Wall of the slot parallel to said Wall, said bar having on its side facing the shaft lengthwise teeth engaged with the shaft teeth for displacing the bar in its plane by rotation of the shaft, the opposite side of the bar being substantially flat and defining a narrow gap with the adjacent slot wall, one end of said .plate being inserted into said gap between the flat s ide of the bar and said adjacent slot wall for clamping said plate end between said bar and said wall and the opposite end of said plate being inserted between the coacting teeth of the shaft and the bar in engagement with said teeth, rotation of the shaft in a predetermined direction displacing the bar and said opposite plate end deeper into said slot While said one plate end remains substantially stationary in reference to the bar thereby tensioning the plate about the cylinder.

2. A device according to claim 1 whereby the slot wa'll facing the substantially flat side of said bar has a length wise groove, and comprising a bendable printing plate having at its end to be inserted into said gap a lengthwise extending protrusion engageable with said groove.

3. A device according to claim 1 wherein -at least one support bar is fitted int-o the slot between the shaft and the adjacent slot wall portion parallel to the axis of the shaft, said support bar supporting the shaft along the length thereof.

4. A device according to claim 1 wherein two support bars are provided in said slot circumferentially spaced in reference to the shaft and disposed substantially opposite to said engaged teeth.

5. A device according to claim 1 and comprising a drive means rotating said shaft, said drive means including a self-arresting gear drive.

References Cited by the Examiner UNITED STATES PATENTS 1,774,169 8/ 1930' Chappell 51-368 1,853,208 4/1932 Harrold 101-415 2,119,279 5/1938 Ker-r et al 101-415 X 2,186,764 1/1940 Meisel 10l415 3,020,842 2/1962 Neal 101-415 3,125,023 3/1964 Skinner et a1 101-415 FOREIGN PATENTS 5,255 2/ 1903 Great Britain.

ROBERT E. PULFREY, Primary Examiner.

J. R. FISHER, Assistant Examiner. 

1. A DEVICE FOR TAUTLY CLAMPING A BENDABLE PRINTING PLATE ABOUT THE CYLINDER OF A PRINTING PRESS, SAID DEVICE COMPRISING A CYLINDER HAVING A LENGTHWISE PERIPHERAL SLOT, A SHAFT ROTATABLY SUPPORTED IN SAID SLOT, SAID SHAFT HAVING SEVERAL LENGTHWISE PERIPHERAL TEETH, A CLAMPING BAR FITTED BETWEEN SAID SHAFT AND ONE SIDE WALL OF THE SLOT PARALLEL TO SAID WALL, SAID BAR HAVING ON ITS SIDE FACING THE SHAFT LENGTHWISE TEETH ENGAGED WITH THE SHAFT TEETH FOR DISPLACING THE BAR IN ITS PLANE BY ROTATION OF THE SHAFT, THE OPPOSITE SIDE OF THE BAR BEING SUBSTANTIALLY FLAT AND DEFINING A NARROW GAP WITH THE ADJACENT SLOT WALL, ONE END OF SAID PLATE BEING INSERTED INTO SAID GAP BETWEEN THE FLAT SIDE OF THE BAR AND SAID ADJACENT SLOT WALL FOR CLAMPING SAID PLATE END BETWEEN SAID BAR AND SAID WALL AND THE OPPOSITE END OF SAID PLATE BEING INSERTED BETWEEN THE COACTING TEETH OF THE SHAFT AND THE BAR IN ENGAGEMENT WITH SAID TEETH, ROTATION OF THE SHAFT IN A PREDETERMINED DIRECTION DISPLACING THE BAR AND SAID OPPOSITE PLATE END DEEPER INTO SAID SLOT WHILE SAID ONE PLATE END REMAINS SUBSTANTIALLY STATIONARY IN REFERENCE TO THE BAR THEREBY TENSIONING THE PLATE ABOUT THE CYLINDER. 